Various vehicular self propelled aerial work platforms have been proposed wherein a pedestal or housing is mounted on a turntable carried by a vehicle. A boom assembly, having a work platform mounted on its outer end, is either pivotally connected directly to the pedestal or through suitable linkage. While these known mobile aerial work platforms have been generally satisfactory for their intended purpose, they have been characterized by their size and reach capabilities thereby precluding their use in relatively small work areas, such as, in warehouses and manufacturing plants having low and narrow doorways and narrow aisles, but requiring high working heights.
After considerable research and experimentation, the vehicular self propelled work platform of the present invention has been devised having a low profile and a narrow width so that it can be maneuvered through low and narrow doorways and aisles in warehouses and manufacturing plants. The vehicular low profile self propelled aerial work platform of the present invention comprises, essentially, a turntable mounted on a vehicle chassis and positioned in a horizontal plane in close proximity to the axles of the vehicle. A parallelogram linkage including a pair of tubular arms is provided between a superstructure support frame carried by the turntable and a riser frame assembly to which one end of a telescopic boom assembly is pivotally connected, the aerial work platform being mounted on the outermost end of the telescopic boom assembly. A counterweight is detachably connected to the support frame and is formed with a trough aligned with a similar trough formed by closely spaced side walls on the superstructure support frame. The tubular arms extend through the troughs when the telescopic boom assembly is lowered to a negative angle for easy access to the work platform. When in this lowered position, for example, the height of the vehicle and associated linkage is approximately eight and a half feet for a machine that provides a work platform height of sixty feet thereby allowing the assembly to pass through nine foot doorways.
The support frame, tubular arms, riser frame assembly and pivotal connection of the telescopic boom to the rise frame assembly are constructed and arranged to be symmetrical with respect to the centerline of the machine whereby load stresses are equally distributed from the telescopic boom to the riser assembly through the tubular arms superstructure side walls and turntable to the chassis. When in the elevated position, the riser frame assembly, tubular arms, superstructure support frame and counterweight are positioned within the wheelbase of the vehicle, to thereby provide a zero tailswing; that is, no component extends beyond the wheels of the vehicle during the sluing of the superstructure and the telescopic boom assembly.